In the art of computing, it is desirable to encrypt data stored on persistent storage media, such as hard disk drives. Encryption protects the data from unauthorized access, and theft of the media upon which the data is stored.
Data is encrypted using encryption keys, and it is desirable to periodically rotate encryption keys. For data that is already encrypted, the key rotation process comprises reading data encrypted with the old encryption key from the storage media, decrypting the data using the old key, encrypting the data with the new key, and writing the data encrypted with the new key back to the storage media. It is desirable to have the ability to perform key rotation while the system continues normal operation
In the art of computing, it is also desirable to provide redundancy so that operation of a computer system can continue after the failure of a component. One method known in the art for enhancing storage redundancy is to provide two or more storage controllers for each storage media device. In the event that one of the storage controllers fails, operation can continue since each storage media device continues to have at least one functioning storage controller.